On the Critical Role of Crop Physiology in Making Sense of Terabites of Gene Information Toward Crop Improvement.

Although crop physiology is no longer a leading discipline in biological research, its role in a putative second Green Revolution (GR) remains critical in an era where gene identification is becoming common place while far less is known about gene function and organization into cell/organ based processes and mechanisms. Here, we argue the case, taking example from on-going efforts in drought research.

We hypothesize that traits contributing to crop adaptation to water limitation relate to basic processes at the plant/organ/cell level as to how plants manage water to maximize return (yield). There, the following domains are critical: water conservation, higher/more timely use of soil water. For instance, we showed that plant control of water losses (lower conductance) when water is non-limiting for plant growth ensures more water availability for grain filling, which is critical for terminal drought adaptation. There, aquaporins could play a critical role in regulating leaf water losses. This dissection of traits of adaptation to limited water contributes to a better understanding of the GxE interactions and opens a range of breeding and molecular genetics avenues. 

While dissecting traits, we paid utmost care to integrate the crop physiology efforts in a breeding perspective. The knowledge gained from physiological research was indeed applied toward the development of accurate, precise and large scale phenotypic methods, suitable for plant breeders and making plant breeding more efficient and precise. For example, we have developed a facility at ICRISAT for a direct, precise, and rapid in-vivo assay of water uptake and yield in a field-like situation (http://www.icrisat.org/bt-root-research.htm). It allows screening reference sets of germplasm, populations, transgenics and near-isogenic lines. This is a quantum leap in method and approach to root systems, to tackle their functionality and harness their highly dynamic nature, and which put crop physiology within reach of breeding efforts.